Abstract
Arabidopsis thaliana metal tolerance protein 1 (AtMTP1, 43 kDa) is a member of the cation diffusion facilitator (CDF) family. We previously reported that AtMTP1 was localized in vacuolar membranes and play a key role for Zn tolerance. The transport mechanism of this attractive transporter is unclear. To analyze the transport mechanism, we established heterologous expression system of AtMTP1 in a Zn-sensitive zrc1cot1 double mutant strain of Saccharomyces cerevisiae. Expression of AtMTP1 complemented the zinc tolerance in the strain. Furthermore, spatial dynamics of Zn2+ concentration in yeast AtMTP1/zrc1cot1 by using the membrane-permeable fluorescent Zn2+ probe also indicate the Zn2+ accumulation in vacuoles. The analysis of Arabidopsis transformed with a promoter-GUS construct suggests that AtMTP1 is highly expressed in growing cells. AtMTP1 may sequestrate zinc in the cytosol to vacuoles in growing cells to maintain the zinc homeostasis.
